For example, in the following Patent Document 1, there is disclosed a corrugated paperboard sheet feeding apparatus capable of holding an end, e.g., front and rear ends, of each of a plurality of corrugated paperboard sheets stacked in a hopper, in such a manner as to separate top-side ones of the corrugated paperboard sheets from bottom-side ones of the corrugated paperboard sheets to form a plurality of separate groups in an up-down direction, thereby reducing a load to be imposed on a bottommost one of the corrugated paperboard sheets, and cause the corrugated paperboard sheets to sequentially move toward the side of a bottom end of the hopper.
As illustrated in FIG. 7, the corrugated paperboard sheet feeding apparatus 100 disclosed in the Patent Document 1 comprises a front guide 101, a back guide 107, and two holding rollers 103, 104 disposed offset in an up-down direction, wherein the holding rollers 103, 104 are configured to come into contact, respectively, with a front end and a rear end of each of a plurality of corrugated paperboard sheets 102 stacked between the front guide 101 and the back guide 107, to separate top-side ones of the corrugated paperboard sheets 102 from bottom-side ones of the corrugated paperboard sheets 102 so as to form three separate groups in the up-down direction. The two holding rollers 103, 104 are pivotally and rotatably supported, respectively, by the front guide 101 and the back guide 107 disposed opposed to each other. Each of the holding rollers 103, 104 has an outer peripheral surface formed with ratchet teeth to increase a friction coefficient with respect to each corrugated paperboard sheet 102. The corrugated paperboard sheet feeding apparatus 100 further comprises a drive device configured to, when a decrease in stacking height of each of two groups of corrugated paperboard sheets 102 located below the respective holding rollers 103, 104 is detected by a respective one of two phototubes 105, 106, rotationally drive the holding rollers 103, 104 to cause downward displacement of the corrugated paperboard sheets 102.